Method of making an electrostatic deflection electrode array

ABSTRACT

An array of electrostatic deflection electrodes comprising parallel bars is produced by cutting parallel grooves in a block which is releasably bonded to a temporary support. The grooves are cut to a depth greater than the thickness of the block leaving portions comprising parallel bars. Following this step, the assembly is inverted and the grooved block is permanently bonded to a support while the temporary support is still bonded to the block to maintain the alignment of the parallel bars comprising the grooved block. The temporary support is then removed. If non-metallic material is used, the bars are metalized in a final step.

United States Patent Greene [4 Aug. 1, 1972 [54] METHOD OF MAKING AN 3,571,919 3/1971 Gleim ..29/580 X ELECTROSTATIC DEF LECTION ELECTRODE ARRAY Primary Examiner-John F. Campbell Assistant Examiner-Richard Bernard Lazarus [72] Ralph E Greene Owensboro Attorney-Nathan J. Cornfeld, John P. Taylor, Frank [73] Ass1gnee: General Electric Company L. Neuhauser, Oscar B. Waddell and Joseph B. For- 22 Filed: May 5,1970

[ 1 pp 3 ,653 57 ABSTRACT An array of electrostatic deflection electrodes com- [52] US. Cl. ..29/25.l4, 29/25.!5, 29/ 25.18 i i ll l b s is produced by cutting parallel grooves in a block is releasably bonded to a [58] Field of Search ..29/25.l, 25.11, 25.13, 25.14, temporary support. The grooves are cut to a depth 29/2515 2518 greater than the thickness of the block leaving por- 423 tions comprising parallel bars. Following this step, the assembly is inverted and the grooved block is per- [56] References cued manently bonded to a support while the temporary UNITED STATES PATENTS support is still bonded to the block to maintain the alignment of the parallel bars comprising the grooved 2,646,521 7/1953 Ra chman ..29/25. 17 X block The temporary Support is then removed If 3,054,709 9/1962 Freeslone et a] "29/583 X metallic material is used, the bars are metalized in a 3,456,335 7/1969 Hennmgs ..29/580 X final step 3,531,857 10/1970 Iwamatsu ..29/423 X I 3,559,282 2/1971 Lesk ..29/580 X 10 Claims, 5 Drawing Figures PATENTEUAUB 1 I9 2 FIG.2.

MACHINE BLOCK TO THICKNESS AND PARALLEL/SM TOLERANCE RELEASABLY SECURE BLOCK TO TEMPORARY SUPPORT CUT PARALLEL GROVES IN BLOCK TO DEPTH EXCEED/N6 THICKNESS OF BLOCK MOUNT BLOCK TO INSULATING SUPPORT REMO VE TEMPORARY SUPPORT METALLIZE NON-METALLIC BLOCK F'IG.3.

INVENTOR:

' RALPH F. GREENE,

l wl f HIS ATTORNEY.

METHOD OF MAKING AN ELECTROSTATIC DEFLECTION ELECTRODE ARRAY BACKGROUND OF THE INVENTION This invention relates to an electron beam tube having a compound lens system comprising a plurality of focusing and deflecting electrodes in a matrix for precise control of the electron beam. More particularly, the invention relates to a method of making an array of deflection electrodes for a compound lens system.

A system for precise control of an electron beam is described in a paper by S. P. Newberry entitled Problems of Microspace Information Storage, appearing in the Fourth Electron Beam Symposium (March 29-30, 1962) published by Alloyd Electronics Corporation, Boston, Mass, and again in The Flys Eye Lens A Novel Electron Optical Component for Use With Large Capacity Random Access Memories by S. P. Newberry in Volume 29 of the American Federation of Information Processing Societies, Conference Proceedings, published by Spartan Books, Washington, DC. (November 1966). The system therein described comprises an ultrahigh density memory wherein impingement of an electron beam on a storage medium is controlled by an objective lens made up of a matrix of minute electron optical lenses, herein referred to as lenslets. This matrix of lenslets is superficially similar in appearance to the compound eye of an ordinary housefly and therefore is designated a Flys Eye Lens. By utilizing coarse deflection of the electron beam so as tostrike only a desired lenslet of the matrix, the lenslet, thus struck, positions the beam to ultimately impinge upon the storage medium at the desired point. Although the coarsely deflected beam may not strike the desired lenslet at. dead center, the accuracy with which the beam strikes the storage medium remains unimpaired so long as even a portion of the beam strikesthe desired lenslet.

Briefly, the planar array of lenslets comprises three parallel plates with a plurality of axially aligned openings therein to form an array of Einzel lenses for fine focusing and, immediately following the array of lens, a matrix of X and Y deflection plates for fine deflection. The resultant ultrahigh resolution electron beam tube can be used, for example, in apparatus for the fabrication of integrated circuits such as described and claimed in US. Pat. No. 3,491,236 issued Jan. 20, 1970 and assigned to the assignee of this invention.

The X-Y deflection array comprises two sets of parallel deflection bars orthogonal to one another and electrically coupled respectively to horizontal and vertical control circuitry. Alternate bars in each set are electrically coupled respectively to the positive and negative terminals of the particular deflection circuit to form the negative and positive deflection electrodes. Thus, the electron beam emanating from any one or more of the Einzel lens passes through a pair of horizontal deflection bars and a pair of vertical deflection bars.

It has been proposed to construct such a deflection electrode array by individually attaching accurately machined bars individually to an insulating substrate. Problems such as inaccurate spacing, warpage due to uneven heating, and overall time and expense have made this solution undesirable.

SUMMARY OF THE INVENTION It is therefore an object of this invention to provide a method of making an accurately spaced deflection electrode array. It is another object of this invention to provide a method of making an array of parallel bars. Other objects of the invention will become apparent from the description.

Briefly considered, in accordance with the invention, a method of making an array of deflection electrodes is provided comprising accurately spaced bars mounted in electrically insulated relationship on a support. The array is formed by releasably mounting a block having predetermined dimensions to a temporary support and then cutting parallel and equally spaced grooves in the block to a depth slightly in excess of the thickness of the block. The cut block is then mounted to the insulating support and the temporary support is removed, leaving an array of accurately spaced bars mounted to the insulated support. When the material used in forming the bars is non-metallic, the bars are then metalized by depositing an adherent metallic film thereon.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an illustration of apparatus embodying the deflection electrode array produced by the invention.

FIG. 2 is a flow sheet describing the process of the in vention.

FIG. 3 is a front elevation illustrating a step in the invention.

FIG. 4 is a front cross-sectional elevation illustrating a later step in the invention.

FIG. 5 is an isometric view of the final product.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, a device is generally illustrated in which the deflection electrode array formed by the invention maybe used. A vacuum enclosure is generally indicated at 2 wherein a beam 4 of charged particles such as an electron beam produced by an electron emitting source 6- is controllably deflected thru a compound lens system onto a target 20 such as a photosensitive coating on a semiconductor wafer.

Beam 4 produced by electron source 6 passes through a beam limiting aperture 8 and is collimated by an electrostatic condenser lens 10. The beam is then coarsely deflected in the X and Y planes respectively, by deflection plates 12a, 12b, and 14a, 14b. The particular electron optics used to direct the beam to each lenslet may, of course, be varied and optimized using various structures and techniques forming no part of the present invention.

The compound lens structure is generally indicated at 30 in FIG. 1. The electrostatic focusing lens structure generally comprises three parallel plates 32, 34, 36, each having an array of openings therethrough in axial alignment to form an array of electrostatic lenses- Immediately following the focusing lens array is the fine deflection system toward which this invention is directed. Briefly, the deflection system comprises a first set of parallel bars immediately followed by a second set of parallel bars at right angles to the first set of bars. The bars thus form a criss-cross array or lattice having dimensional registration to the openings in the lens plates to provide a fine X-Y deflection system for each lens. Thus, maintenance of even and parallel spacing of the deflection bars is desirable.

Referring now to the flow sheet of FIG. 2 and the illustration of FIG. 3, a block 40 is illustrated in FIG. 3 releasably bonded to a support 50. Block preferably comprises forsterite ceramic but may be any material which is machinable, capable of being bonded to a final support, and of matching temperature coefficient to the permanent support if brazing or other high temperature bonding is contemplated, or if operation of the device at other than ambient temperature is desired.

Ceramic block40 is dimensioned to conform to the overall dimensions of one set of the desired parallel electrode bars forming the array. For example the thickness of block 40 conforms ,to the depth or thickness of the deflection bars to be formed therefrom, the width of block 40 conforms to the sum of the width of the deflection bars plus the spacing therebetween, and the length of block 40 is equal to or greater than the desired total length of the deflection bars. When the length of block 40 exceeds the desired finished length, the excess amount can be trimmed off after the grooves are cut. This procedure is actually preferable to insure uniformity of the grooves and bars at the ends of block 40.

The purpose of temporarily bonding block 40 to support 10 is to allow block 40 to be cut into separate bars while maintaining the spacing between the so-formed bars until the bars are subsequently mounted on a permanent support. A releasable bond is therefore made between block 40 and support 50. Preferably, an organic adhesive such as, for example, paraffin, an acrylic resin, or an epoxy resin is used which is subsequently removable, such as by thermal or chemical decomposition after sealing or mounting of the bars to a permanent support. Alternatively, the adhesive can be one which is chemically removable after mounting of the bars to a permanent support. In a particular example, an epoxy resin, Epon 828, was used with a modified amine curing agent (agent U).

Following the temporary mounting of block 40 to temporary support 50, the resulting subassembly is mounted to a suitable jig and parallel grooves are cut in the face of block 40 along the entire length of block 40. Each groove is cut to a depth at least as deep as the thickness of block 40 and preferably slightly in excess thereof, to cut slightly into support 50 without cutting entirely through support 50. As shown in FIG. 3, a ganged blade cutter 60 comprising parallel blades 62 each having straight sides Y64 and 66 is used to cut the grooves in block 40 wherein the sidewalls of each groove are approximately 90 to the top surface of block 40.

When forsterite ceramic, for example, is used as the material for block 40, the blades 62 preferably comprise diamond impregnated blades. Other suitable blade materials can also be used depending upon the choice of the material comprising block 40.

Ganged blade cutter 60 is dimensioned to cut parallel grooves of substantially identical depth, width and spacing. For example, to form parallel bars of approximately 0.060 inch width with 0.020 inch spacing therebetween, the adjacent grooves are cut as 0.020 inch wide grooves spaced 0.080 inch apart centerto center.

After the grooves are cut and the desired bars formed thereby, the subassembly is removed from the jig and the bars are mounted to a permanent support.

Referring to FIGS. 4 and 5 bars 80 are mounted on a permanent support which may be made of forsten'te ceramic. Support 70 may be cylindrical as shown in FIG. 5 or rectangular with a central cutout, its function being to peripherally support bars without interferring with the passage of electron beams through the openings between the bars as shown in FIG. 1.

Bars 80 can be mounted on the end of support 70, or, as shown in FIGS. 4 and 5 are preferably mounted in a notch or lip 72 cut into two opposing portions of one end of support 70. When bars 80 and support 70 comprise forsterite' ceramic, they may be sealed to one another using titanium-nickel active alloy techniques such as described and claimed in Beggs US. Pat. No. 2,857,663 issued Oct. 28, 1958 and assigned to the assignee of this invention.

In a specific example, a subassembly comprising bars 80 was mounted to a support 70 such as illustrated in FIGS. 4 and 5 by placing about a 5 mil layer of a paste comprising finely divided particles of a 70 percent by weight titanium 30 percent by weight nickel alloy dispersed in a solvated Isobutylrnethacrylate resin on lip 72 of support 70. The subassembly was then placed on lip 72 with bars 80 in contact with the paste. The subassembly was then temporarily secured to support 70 by a clamping mechanism and then placed in a vacuum furnace (l0' mm Hg) and heated to about 1,000C for about 8 minutes to bond'bars 80 to support 70. The furnace was cooled and the ,clamped subassembly removed. The clamping mechanism was then taken off. The subassembly, which then comprised bars 80 brazed on one side to support 70 and having temporary support 50 still attached to the opposite side of the bars, was next air fired in a furnace at 500700C for 30 minutes to remove support 50 andv to remove any residual carbon.

To form the deflection electrode array described earlier, a second set of bars is produced in the same manner set forth above. This set of bars is mounted on a support 70 in the same manner as described above. The two supports 70 and 70' are then mounted to one another so that bars 80 on support 70 and bars on support 70' are parallel and orthogonal to one another to form a lattice like array.

When non-metallic materials are used to form bars 80, as in the example, the bars may be metalized after they have been bonded to support 70. This can be done using techniques such as electroless plating well known in the art. When a metallic sheet is used, this step is omitted. The purpose of metalizing the ceramic bars is to provide a conducting surface thereon so that each bar can be used as an electrode.

As more fully discussed in said Newberry patent referred to above, the parallel electrode bars are alternately, connected to the positive or negative terminals of a power source to provide electrostatic deflection of an electron beam passing therethrough. It is therefore necessary, after metalizing the assembly, to electrically isolate each bar from adjacent bars. This can be done, for example, manually by scribing or scraping away portions of the metalized surface between bars 80 on support 70 or alternatively by appropriate masking techniques during the metalizing step.

As a final step, an appropriate electrical connection is made to alternate bars to connect, for example, even numbered bars to the positive terminal and odd numbered bars to the negative terminal.

These steps are repeated for the second set of bars mounted on their support. One set of bars is then energized by a power source to control the X-axis deflection of the electron beam while the second set of bars is energized by a power source to control Y-axis deflection of the beam.

Thus, the invention comprises a process for the formation of an array of parallel and equally spaced bars cut from a common sheet of material temporarilyheld to a support to maintain the parallel spacing of the formed bars until the bars are mounted to a permanent support. The resulting array of bars can be mounted orthogonal and in a parallel plane to a second set of I bars to fonn a deflection electrode array useful in a compound lens system.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A method of making an array of deflection electrodes for an electron beam tube comprising accurately spaced bars mounted in electrically insulated relationship on a support comprising the steps of:

a. releasably mounting a block having predetermined dimensions to a temporary support member;

b. forming parallel and equally spaced grooves of equal width in said block of a depth sufficient to sever said block into parallel and equally spaced apart remaining portions of equal width;

c. mounting said remaining portions of said cut block to an insulative support structure;

d. removing said temporary support member, and electrically connecting together alternate portions of said cut block to form an array of positive and negative deflection electrodes;

e. and mounting said array of deflection electrodes in an electron beam tube.

2. The process of claim 1 wherein which said block comprises ceramic and selected portions of the ceramic are metalized after cutting said block.

3. A method of making an array of deflection electrodes for an electron beam tube comprising accurately spaced bars mounted in electrically insulated relationship on a support comprising the steps of:

a. releasably mounting a block having predetermined dimensions to a temporary support member to form a temporary assembly;

b. forming parallel and equally spaced grooves of equal width in said block of said assembly of a depth at least equal to the thickness of said block to form accurately spaced bars;

c. thereafter mounting said bars fomled from said block to a support structure while said bars remain attached to said temporary support member;

d. then removing said temporary support member to provide an array of deflection electrodes; and

e. mounting said array of deflection electrodes in an electron beam tube.

4. The method of claim 3 wherein said grooves are formed in said assembly to a depth in excess of the thickness of said block.

5. The method of making an array of deflection electrodes for an electron beam tube comprising accurately spaced bars mounted in electrically insulated relationshi on su rt om sin the ste sof:

3? re easel y n b ig a cerarrric block having b. forming parallel and equally spaced grooves of equal widths in said block and said support member of a depth in excess of the thickness of said block without severing said support member to divide said block into parallel portions of equal width and equal spacing;

c. thereafter bonding said portions of said block to a ceramic support structure;

d. then removing said temporary support member;

and

e. metallizing said remaining portions of said ceramic block; thereby forming an array of deflection electrodes mounted in insulated relationship to said ceramic support structure with accurate alignment of the electrodes due to the accurate formation of the grooves; and

f. mounting said array of deflection electrodes in an electron beam tube.

6. The method of claim 3 wherein said block is mounted in electrically insulated relationship to said support structure.

7. The method of claim 3 wherein said block comprises ceramic material and said bars are metalized.

8. The method of claim 7 wherein said ceramic bars are bonded to a ceramic support structure.

9. The method of claim 3 wherein said temporary support member is bonded to said block by a decomposable bonding material.

10. The method of claim 9 wherein said block is bonded to said support by an epoxy resin. 

2. The process of claim 1 wherein which said block comprises ceramic and selected portions of the ceramic are metalized after cutting said block.
 3. A method of making an array of deflection electrodes for an electron beam tube comprising accurately spaced bars mounted in electrically insulated relationship on a support comprising the steps of: a. releasably mounting a block having predetermined dimensions to a temporary support member to form a temporary assembly; b. forming parallel and equally spaced grooves of equal width in said block of said assembly of a depth at least equal to the thickness of said block to form accurately spaced bars; c. thereafter mounting said bars formed from said block to a support structure while said bars remain attached to said temporary support member; d. then removing said temporary support member to provide an array of deflection electrodes; and e. mounting said array of deflection electrodes in an electron beam tube.
 4. The method of claim 3 wherein said grooves are formed in said assembly to a depth in excess of the thickness of said block.
 5. The method of making an array of deflection electrodes for an electron beam tube comprising accurately spaced bars mounted in electrically insulated relationship on a support comprising the steps of: a. releasably bonding a ceramic block having predetermined dimensions to a temporary support member with a decomposable bonding material; b. forming parallel and equally spaced grooves of equal widths in said block and said support member of a depth in excess of the thickness of said block without severing said support member to divide said block into parallel portions of equal width and equal spacing; c. thereafter bonding said portions of said block to a ceramic support structure; d. then removing said temporary support member; and e. metallizing said remaining portions of said ceramic block; thereby forming an array of deflection electrodes mounted in insulated relationship to said ceramic support structure with accurate alignment of the electrodes due to the accurate formation of the grooves; and f. mounting said array of deflection electrodes in an electron beam tube.
 6. The method of claim 3 wherein said block is mounted in electrically insulated relationship to said support structure.
 7. The method of claim 3 wherein said block comprises ceramic material and said bars are metalized.
 8. The method of claim 7 wherein said ceramic bars are bonded to a ceramic support structure.
 9. The method of claim 3 wherein said temporary support member is bonded to said block by a decomposable bonding material.
 10. The method of claim 9 wherein said block is bonded to said support by an epoxy resin. 